Luling Skies Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Luling Skies Observatory clear sky chart from 2005-11-06 to 2026-07-16.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	10% 6% 3 7% 5% 5% 6% 5% 7% 9% 37%	137054
	Night	10% 6% 2 6% 4 4 4 4 6% 8% 45%	135665
Transparency	Day	38% 9% 14% 18% 15% 6%	140727
	Night	35% 8% 14% 19% 17% 8%	140057
Seeing	Day	11% 6% 18% 25% 24% 16%	16870
	Night	11% 5% 18% 31% 27% 8%	26417

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 5% 4 7% 5% 5% 5% 4 7% 8% 37%	5289
	11th to 20th	Day	11% 7% 2 5% 4 4 4 3 5% 6% 48%	5398
	21st to end	Day	19% 9% 3 8% 4 4 5% 3 5% 5% 35%	6436
February	1st to 10th	Day	13% 9% 2 7% 5% 5% 4 4 5% 7% 39%	2100
	11th to 20th	Day	14% 8% 2 7% 3 3 4 3 6% 8% 41%	2048
	21st to end	Day	15% 8% 3 7% 4 5% 5% 3 4 8% 37%	1730
March	1st to 10th	Day	17% 9% 3 7% 5% 4 4 4 5% 7% 35%	4896
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 7% 9% 45%	5090
	21st to end	Day	12% 7% 3 7% 4 4 4 4 5% 6% 43%	5817
April	1st to 10th	Day	10% 6% 2 6% 5% 6% 5% 4 6% 8% 41%	2520
	11th to 20th	Day	11% 6% 3 6% 5% 5% 4 4 6% 9% 41%	2494
	21st to end	Day	7% 5% 3 6% 5% 5% 5% 4 6% 8% 46%	2520
May	1st to 10th	Day	17% 7% 2 7% 5% 5% 5% 4 6% 8% 33%	7021
	11th to 20th	Day	6% 4 2 6% 5% 5% 5% 5% 8% 10% 45%	7031
	21st to end	Day	7% 5% 2 7% 7% 6% 8% 6% 9% 11% 32%	7736
June	1st to 10th	Day	9% 6% 3 10% 7% 6% 7% 6% 8% 9% 28%	2520
	11th to 20th	Day	5% 6% 2 9% 8% 7% 9% 6% 9% 11% 28%	2658
	21st to end	Day	6% 7% 3 9% 9% 8% 8% 8% 9% 10% 24%	2730
July	1st to 10th	Day	6% 6% 3 8% 8% 8% 9% 7% 9% 12% 25%	6030
	11th to 20th	Day	5% 5% 3 10% 9% 9% 9% 8% 9% 11% 22%	5838
	21st to end	Day	5% 6% 3 10% 8% 8% 9% 7% 10% 12% 22%	5922
August	1st to 10th	Day	3 3 2 6% 5% 5% 6% 6% 9% 11% 43%	3905
	11th to 20th	Day	5% 5% 2 7% 6% 6% 8% 6% 10% 12% 33%	3849
	21st to end	Day	7% 7% 3 12% 8% 6% 6% 5% 7% 8% 30%	4312
September	1st to 10th	Day	11% 6% 3 8% 7% 7% 7% 6% 7% 9% 29%	2400
	11th to 20th	Day	10% 6% 3 8% 6% 5% 6% 5% 7% 9% 35%	2350
	21st to end	Day	8% 4 3 7% 5% 4 6% 4 7% 7% 46%	2200
October	1st to 10th	Day	7% 3 2 6% 5% 5% 4 4 6% 7% 52%	2094
	11th to 20th	Day	6% 3 2 6% 4 4 4 4 6% 7% 54%	2000
	21st to end	Day	9% 4 2 5% 3 3 4 3 5% 8% 53%	2200
November	1st to 10th	Day	7% 5% 1 6% 3 4 4 5% 5% 7% 52%	2058
	11th to 20th	Day	9% 6% 1 5% 4 3 4 2 5% 7% 53%	2100
	21st to end	Day	11% 6% 2 6% 4 4 5% 4 6% 7% 43%	1903
December	1st to 10th	Day	17% 7% 3 6% 4 5% 5% 3 5% 5% 40%	3020
	11th to 20th	Day	9% 6% 2 6% 4 4 4 4 5% 8% 49%	3774
	21st to end	Day	14% 7% 3 7% 5% 3 4 3 5% 6% 43%	5065
January	1st to 10th	Night	15% 8% 3 6% 4 4 4 3 4 6% 43%	7614
	11th to 20th	Night	16% 7% 3 5% 4 3 4 3 5% 7% 45%	7563
	21st to end	Night	19% 8% 2 7% 4 4 4 3 5% 7% 36%	7745
February	1st to 10th	Night	13% 7% 3 7% 4 4 4 3 6% 6% 44%	2520
	11th to 20th	Night	18% 7% 3 6% 3 3 3 3 5% 7% 42%	2458
	21st to end	Night	17% 7% 2 6% 4 4 4 3 6% 6% 41%	2076
March	1st to 10th	Night	17% 9% 3 7% 4 4 4 3 4 6% 39%	5219
	11th to 20th	Night	11% 7% 2 5% 4 4 4 4 6% 6% 49%	5090
	21st to end	Night	14% 7% 2 5% 4 3 4 3 5% 6% 47%	5354
April	1st to 10th	Night	13% 7% 2 5% 4 3 5% 4 5% 6% 46%	2100
	11th to 20th	Night	10% 5% 2 6% 4 4 5% 3 5% 7% 48%	2075
	21st to end	Night	5% 4 2 5% 4 4 5% 4 7% 8% 53%	2100
May	1st to 10th	Night	17% 8% 3 8% 4 4 4 4 5% 8% 35%	5832
	11th to 20th	Night	11% 5% 2 6% 4 5% 5% 4 6% 8% 45%	5829
	21st to end	Night	6% 5% 2 7% 5% 5% 5% 5% 8% 12% 41%	6415
June	1st to 10th	Night	7% 5% 2 6% 4 5% 5% 5% 8% 12% 43%	2100
	11th to 20th	Night	4 5% 2 4 5% 5% 5% 5% 8% 12% 46%	1952
	21st to end	Night	5% 5% 2 5% 4 4 4 5% 9% 13% 43%	1890
July	1st to 10th	Night	2 3 2 5% 5% 5% 7% 6% 9% 15% 40%	4168
	11th to 20th	Night	3 3 1 5% 4 4 5% 6% 10% 13% 47%	4227
	21st to end	Night	3 4 2 6% 5% 6% 6% 6% 9% 14% 39%	4929
August	1st to 10th	Night	1 2 1 3 3 3 5% 4 8% 12% 57%	3244
	11th to 20th	Night	3 2 1 5% 4 4 6% 6% 10% 15% 45%	3200
	21st to end	Night	4 5% 2 6% 5% 6% 6% 6% 8% 10% 43%	3586
September	1st to 10th	Night	7% 6% 2 5% 5% 6% 6% 5% 8% 10% 40%	2000
	11th to 20th	Night	7% 4 1 6% 5% 5% 6% 5% 7% 10% 44%	2028
	21st to end	Night	7% 4 2 5% 3 4 4 4 6% 9% 52%	2200
October	1st to 10th	Night	6% 4 2 5% 4 3 4 3 5% 7% 58%	2300
	11th to 20th	Night	6% 3 1 4 3 2 4 3 4 7% 62%	2400
	21st to end	Night	10% 4 2 4 4 3 4 3 4 6% 57%	2640
November	1st to 10th	Night	9% 5% 2 5% 3 4 3 3 4 6% 55%	2460
	11th to 20th	Night	11% 5% 1 4 4 3 4 3 5% 6% 55%	2520
	21st to end	Night	9% 6% 2 6% 4 4 5% 3 5% 6% 49%	2708
December	1st to 10th	Night	12% 7% 3 8% 5% 5% 4 3 4 6% 42%	4380
	11th to 20th	Night	9% 6% 2 5% 4 3 4 4 5% 7% 51%	4627
	21st to end	Night	14% 10% 3 7% 4 4 4 2 4 4 44%	6116

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	41% 7% 11% 17% 18% 6%	5290
	11th to 20th	Day	36% 4 6% 18% 27% 9%	5398
	21st to end	Day	50% 5% 6% 12% 16% 10%	6436
February	1st to 10th	Day	44% 6% 8% 14% 18% 9%	2100
	11th to 20th	Day	40% 7% 10% 18% 18% 8%	2058
	21st to end	Day	45% 6% 10% 14% 18% 6%	1730
March	1st to 10th	Day	46% 6% 9% 16% 14% 9%	4896
	11th to 20th	Day	33% 7% 10% 17% 17% 14%	5090
	21st to end	Day	39% 7% 10% 18% 18% 7%	5819
April	1st to 10th	Day	36% 9% 14% 16% 16% 9%	2520
	11th to 20th	Day	38% 6% 10% 21% 17% 8%	2494
	21st to end	Day	31% 8% 13% 23% 20% 5%	2520
May	1st to 10th	Day	44% 9% 13% 20% 10% 3	7056
	11th to 20th	Day	30% 9% 17% 25% 18% 2	7035
	21st to end	Day	36% 14% 19% 23% 8% 1	7749
June	1st to 10th	Day	44% 11% 15% 20% 10% 1	2520
	11th to 20th	Day	41% 12% 16% 20% 10% 1	2658
	21st to end	Day	46% 13% 18% 17% 6%	2730
July	1st to 10th	Day	41% 15% 26% 15% 2	5966
	11th to 20th	Day	45% 17% 31% 6% 1	5769
	21st to end	Day	45% 16% 19% 18% 2	5752
August	1st to 10th	Day	28% 9% 17% 25% 20%	3893
	11th to 20th	Day	35% 12% 25% 22% 5% 1	3885
	21st to end	Day	48% 11% 14% 14% 11% 2	4311
September	1st to 10th	Day	44% 12% 17% 13% 10% 3	2400
	11th to 20th	Day	41% 9% 15% 16% 15% 4	2350
	21st to end	Day	34% 8% 12% 22% 15% 9%	2200
October	1st to 10th	Day	28% 4 7% 13% 22% 25%	3406
	11th to 20th	Day	17% 4 7% 21% 28% 23%	3240
	21st to end	Day	19% 5% 8% 13% 41% 14%	3538
November	1st to 10th	Day	29% 5% 9% 22% 25% 9%	2058
	11th to 20th	Day	31% 5% 6% 20% 24% 13%	2100
	21st to end	Day	37% 7% 9% 19% 19% 10%	1903
December	1st to 10th	Day	45% 5% 9% 15% 22% 4	3020
	11th to 20th	Day	33% 6% 9% 21% 22% 8%	3772
	21st to end	Day	41% 7% 7% 16% 25% 4	5065
January	1st to 10th	Night	41% 5% 10% 16% 19% 8%	7615
	11th to 20th	Night	39% 4 5% 17% 24% 11%	7563
	21st to end	Night	48% 4 9% 12% 18% 9%	7745
February	1st to 10th	Night	41% 5% 8% 17% 20% 10%	2520
	11th to 20th	Night	43% 5% 8% 15% 18% 11%	2459
	21st to end	Night	42% 6% 11% 15% 16% 11%	2076
March	1st to 10th	Night	46% 6% 9% 12% 17% 10%	5219
	11th to 20th	Night	33% 7% 10% 16% 19% 15%	5090
	21st to end	Night	37% 6% 10% 21% 19% 8%	5354
April	1st to 10th	Night	37% 6% 13% 18% 16% 11%	2100
	11th to 20th	Night	35% 6% 11% 22% 17% 9%	2075
	21st to end	Night	28% 6% 14% 24% 23% 6%	2100
May	1st to 10th	Night	45% 8% 12% 19% 12% 3	5862
	11th to 20th	Night	34% 8% 16% 25% 16% 2	5830
	21st to end	Night	32% 11% 21% 26% 8% 1	6427
June	1st to 10th	Night	31% 10% 18% 27% 13%	2100
	11th to 20th	Night	27% 12% 21% 27% 12%	1952
	21st to end	Night	29% 12% 27% 24% 8%	1890
July	1st to 10th	Night	29% 13% 37% 19% 2	4125
	11th to 20th	Night	24% 16% 48% 10% 2	4176
	21st to end	Night	31% 17% 26% 24% 2	4785
August	1st to 10th	Night	16% 10% 25% 31% 18%	3232
	11th to 20th	Night	22% 13% 35% 27% 2	3230
	21st to end	Night	35% 12% 20% 20% 10% 3	3586
September	1st to 10th	Night	34% 12% 22% 17% 12% 3	2000
	11th to 20th	Night	32% 11% 16% 20% 16% 6%	2028
	21st to end	Night	28% 7% 15% 27% 15% 9%	2200
October	1st to 10th	Night	28% 4 8% 15% 22% 23%	3755
	11th to 20th	Night	15% 4 6% 21% 30% 24%	3899
	21st to end	Night	19% 3 7% 11% 41% 18%	4252
November	1st to 10th	Night	30% 6% 7% 22% 25% 11%	2460
	11th to 20th	Night	31% 4 8% 18% 27% 13%	2520
	21st to end	Night	34% 6% 8% 20% 22% 10%	2708
December	1st to 10th	Night	43% 4 7% 19% 21% 6%	4380
	11th to 20th	Night	32% 6% 11% 21% 19% 11%	4628
	21st to end	Night	44% 6% 8% 14% 22% 7%	6116

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 15% 33% 27% 6% 2	330
	11th to 20th	Day	13% 17% 32% 28% 9% 1	330
	21st to end	Day	23% 13% 36% 23% 4 1	363
February	1st to 10th	Day	16% 12% 38% 25% 8% 1	330
	11th to 20th	Day	21% 15% 32% 20% 10% 1	330
	21st to end	Day	11% 19% 42% 20% 8%	273
March	1st to 10th	Day	15% 15% 35% 28% 7% 1	330
	11th to 20th	Day	19% 14% 32% 26% 9% 1	330
	21st to end	Day	14% 9% 31% 32% 12% 2	468
April	1st to 10th	Day	13% 11% 32% 31% 12% 1	540
	11th to 20th	Day	15% 11% 30% 26% 16% 2	532
	21st to end	Day	6% 7% 27% 34% 21% 4	540
May	1st to 10th	Day	12% 8% 22% 30% 23% 5%	543
	11th to 20th	Day	8% 5% 22% 30% 27% 9%	567
	21st to end	Day	6% 3 11% 31% 33% 17%	617
June	1st to 10th	Day	9% 2 11% 24% 31% 22%	570
	11th to 20th	Day	8% 3 9% 25% 35% 21%	708
	21st to end	Day	7% 1 8% 25% 33% 26%	780
July	1st to 10th	Day	10% 2 5% 18% 34% 31%	771
	11th to 20th	Day	7% 2 4 12% 35% 40%	694
	21st to end	Day	8% 1 4 14% 32% 41%	576
August	1st to 10th	Day	4 1 3 15% 36% 41%	526
	11th to 20th	Day	9% 1 3 10% 29% 49%	519
	21st to end	Day	9% 3 8% 15% 33% 33%	583
September	1st to 10th	Day	11% 2 7% 18% 35% 28%	530
	11th to 20th	Day	11% 2 7% 21% 37% 22%	530
	21st to end	Day	8% 3 8% 27% 37% 18%	530
October	1st to 10th	Day	6% 3 15% 39% 28% 9%	424
	11th to 20th	Day	5% 3 17% 38% 25% 11%	330
	21st to end	Day	15% 6% 21% 31% 21% 6%	363
November	1st to 10th	Day	12% 5% 19% 32% 26% 5%	330
	11th to 20th	Day	15% 6% 25% 30% 18% 5%	330
	21st to end	Day	14% 10% 32% 28% 12% 3	330
December	1st to 10th	Day	18% 9% 32% 23% 12% 6%	330
	11th to 20th	Day	15% 10% 35% 31% 8% 1	330
	21st to end	Day	20% 8% 31% 25% 13% 2	363
January	1st to 10th	Night	18% 9% 30% 35% 8% 1	1043
	11th to 20th	Night	17% 9% 26% 39% 9%	1011
	21st to end	Night	19% 9% 34% 32% 6%	924
February	1st to 10th	Night	16% 8% 31% 37% 8% 1	840
	11th to 20th	Night	21% 9% 30% 30% 9%	823
	21st to end	Night	18% 11% 35% 31% 5%	692
March	1st to 10th	Night	14% 11% 31% 33% 11%	722
	11th to 20th	Night	14% 4 29% 37% 16% 1	630
	21st to end	Night	10% 8% 25% 39% 18%	693
April	1st to 10th	Night	14% 10% 25% 38% 13% 1	630
	11th to 20th	Night	12% 8% 27% 35% 17% 1	623
	21st to end	Night	6% 5% 23% 43% 22% 1	630
May	1st to 10th	Night	10% 4 19% 43% 25% 1	630
	11th to 20th	Night	8% 3 14% 43% 29% 3	621
	21st to end	Night	7% 2 10% 34% 39% 9%	683
June	1st to 10th	Night	8% 2 5% 34% 43% 9%	630
	11th to 20th	Night	4 1 5% 24% 52% 13%	630
	21st to end	Night	7% 1 6% 20% 45% 20%	630
July	1st to 10th	Night	6% 1 4 11% 50% 28%	615
	11th to 20th	Night	5% 1 1 6% 52% 36%	597
	21st to end	Night	5% 1 2 13% 50% 29%	657
August	1st to 10th	Night	2 1 11% 49% 37%	597
	11th to 20th	Night	4 1 2 9% 45% 38%	594
	21st to end	Night	6% 1 5% 15% 46% 27%	660
September	1st to 10th	Night	9% 1 4 18% 47% 22%	600
	11th to 20th	Night	8% 1 4 23% 50% 13%	628
	21st to end	Night	9% 2 7% 28% 45% 9%	800
October	1st to 10th	Night	7% 2 11% 38% 36% 6%	800
	11th to 20th	Night	7% 4 16% 35% 33% 6%	800
	21st to end	Night	11% 4 19% 36% 27% 3	880
November	1st to 10th	Night	10% 5% 13% 41% 28% 3	820
	11th to 20th	Night	14% 4 20% 39% 22% 2	840
	21st to end	Night	11% 6% 26% 37% 18% 1	840
December	1st to 10th	Night	16% 8% 26% 32% 18% 1	840
	11th to 20th	Night	15% 6% 25% 40% 14% 1	840
	21st to end	Night	20% 9% 26% 33% 11% 1	924

Page generated at 2026-07-13 02:14:53. Version ac07

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